Party wall procedure against planning for basements

Planning permission for a basement does not entitle you to excavate next to a neighbour's wall. Those are two separate regimes with two separate sets of rights, and the Party Wall etc. Act 1996 operates whether or not the council has granted anything. A landlord who gets permission in March and starts digging in April, without having served notice, has committed a trespass and handed the neighbour an injunction application.

The two processes also run on different clocks. Planning takes eight weeks and is public. The party wall process takes a minimum of a month from notice and is private, between you and the adjoining owner. Run them in the wrong order and you lose the summer.

Two regimes, two sets of rights

Planning controls the use and appearance of land in the public interest. The council weighs amenity, character, drainage, trees and highway safety, and it decides on planning merits.

The Party Wall etc. Act 1996 protects private property rights. It gives you a statutory right to carry out certain works that would otherwise be trespass or nuisance, in exchange for notice, a procedure and a liability to make good damage. The council has no role in it, and the neighbour's rights under the Act survive a planning permission entirely.

This is why a neighbour who objects to a basement on planning grounds and loses can still stop the work. Different question, different forum, different answer.

What the Act controls

Three sections matter for a basement.

Section 1 covers building on the line of junction where there is no existing wall. Section 2 covers works to an existing party wall, including cutting into it, supporting it from below, raising it and inserting a beam. Section 6 covers excavation near an adjoining owner's structure, and for basements it is usually the operative one.

Section 6 has two limbs, and the distinction is about depth and distance. The first applies to excavation within three metres of an adjoining owner's building or structure where the excavation will go below the level of that building's foundations. The second applies within six metres where the excavation would cut a line drawn downwards at 45 degrees from the bottom of the neighbour's foundations. Most residential basements in a terrace engage the first limb; deeper schemes on wider plots engage the second.

Where either limb applies, notice is required, and with a section 6 notice you must provide plans and sections showing the proposed excavation. Underpinning the neighbour's foundations is an option you may offer, and in some cases the adjoining owner can require it.

Notices, awards and surveyors

The sequence is fixed by the Act.

1. Serve notice on every adjoining owner, which includes freeholders and leaseholders with terms over a year. Section 6 notices need at least one month before work starts, section 2 notices at least two months.
2. The adjoining owner has 14 days to consent or dissent. Silence after 14 days counts as dissent, which is the most common outcome.
3. On dissent, a dispute arises under the Act and surveyors are appointed. Either a single agreed surveyor, or one each with a third surveyor selected to resolve disagreement.
4. The surveyors produce an award, which records the works permitted, the conditions, the schedule of condition of the neighbour's property, and how costs are apportioned.
5. Work proceeds in accordance with the award. Either owner can appeal the award to the county court within 14 days of service.

The appointing owner normally pays the surveyors' fees, both sides, because the works are for their benefit. On a basement with three adjoining owners that is three sets of fees and three awards, and the total is a real line in the appraisal rather than a rounding error.

Note that the process cannot be shortcut by agreement in writing between neighbours who are on good terms. It can be simplified, through a single agreed surveyor and a consenting neighbour, but the notice itself is the trigger for the statutory rights and skipping it removes the protection the Act gives you.

Why permission does not authorise excavation

A planning permission is a consent to develop, given in the public interest. It does not grant private rights and it does not override them. The same principle explains why permission does not override a restrictive covenant, a right of light or a want of title.

For basements the practical consequences are three.

Excavation within the section 6 distances without notice is a trespass the neighbour can sue on. The remedy the neighbour seeks is usually an injunction, which stops the work rather than compensating for it, and injunctions on part-excavated basements are expensive in a way that is hard to model.

The party wall award can require works the planning permission did not contemplate. Foundation support to a greater depth, a temporary propping scheme, monitoring with trigger levels, restricted working methods. Some of those change the structural design and a few change the appearance enough to need a planning amendment.

And the council will not enforce the Act for a neighbour, nor will it refuse permission because notice has not been served. Officers correctly treat it as a private matter, which surprises objectors and reassures applicants slightly more than it should.

Sequencing the two processes

The efficient order is to overlap them deliberately rather than run them end to end.

Start the ground investigation and the structural design before the planning application, because the party wall surveyors will want them and the Basement Impact Assessment needs them anyway. What an independent auditor looks for in that assessment is covered in what the auditor checks.

Submit the planning application. While it is under consideration, tell the neighbours informally what is coming and when notice will follow. Do not serve notice yet, because a notice served before the design is settled will be superseded and you will pay for two awards.

Serve notices once permission is granted and the structural scheme is fixed, allowing the statutory period plus realistic time for appointment and award. On a terraced house with two adjoining owners, three to four months from notice to award is a reasonable planning assumption, longer if a third surveyor is needed.

Then discharge the planning conditions that bite before work starts, in parallel with the award process, since both need the same information.

Neighbour engagement that helps both

The same conversation serves both regimes, which is the one genuine efficiency available here.

Tell neighbours early, in person, with drawings. Explain the excavation depth, the construction method, the expected duration, the working hours and who to contact. Offer a schedule of condition survey before anything starts, whether or not the Act requires it, because it protects you as much as them.

Where the scheme includes construction traffic and spoil removal, share that plan too. The volume of lorry movements from a basement is the thing neighbours object to most, and it is also the thing most easily managed by condition. Where the excavation needs pumping, the consents involved are set out in dewatering a basement and when a permit is needed.

What not to do is treat the party wall process as an adversarial one because the neighbour objected to the planning application. The surveyors will reach an award either way, and a hostile process produces a more restrictive award and a slower one.

What the council will and will not consider

The council will consider structural and ground stability effects on neighbouring property as a planning matter, through the basement impact assessment and any Structural Survey it requires. It will consider construction impacts through a construction management plan condition. It will consider hydrogeological effects, tree impacts and highway matters.

It will not consider whether party wall notices have been served, whether the neighbour's foundations are sound, whether compensation has been agreed, or who pays for the surveyors. Objections on those grounds carry no weight, and an officer's report will say so.

The one overlap worth watching is where a party wall award requires works that differ from the approved drawings. Foundation works that change ground levels, a propping scheme that needs a temporary structure in the front garden, or a revised construction sequence that conflicts with an approved method statement all need checking against the permission. A non-material amendment is usually enough, but it needs to be applied for rather than assumed.

Enter your postcode on PlanScope to see which basement and structural reports your project is likely to need.

This is general guidance rather than legal advice. Party wall matters are private legal rights, so check the position with a party wall surveyor or a solicitor, and with your local planning authority on the planning side, before starting work.

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